Message-ID: <25491924.post@talk.nabble.com>
Date: Thu, 17 Sep 2009 07:47:13 -0700 (PDT)
From: rawi <only4com@web.de>
To: pgsql-sql@postgresql.org
Subject: Re: Hibernate, web application and only one sequence for all
	primary keys
In-Reply-To: <4AB23593.4090906@beecom.ch>
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References: <25490498.post@talk.nabble.com> <4AB23593.4090906@beecom.ch>


Leo Mannhart wrote:
> 
> Caveat: If you use the standard sequence generator in hibernate, it is
> not using the postgres-sequence in the "usual" manner. hibernate itself
> caches 50 ID's as sequence numbers by default. This means, hibernate
> only does a select on the database sequence every 50 numbers. it
> multyplies the database sequence by 50 to get the "real" sequence
> number. it generates the sequence numbers in blocks of 50 numbers or
> according to the sequence cache size.
> That said, you would probably not see any performance bottlenecks
> because of the sequence number generator in the database, even with
> thousands of inserts per second.
> 

Hi Leo, thank you for the explanation!

I don't know if it is that cool to lose up to 50 IDs on each session-end of
Hibernate...
And what do you suppose it would happen, if I set the cache size of
Hibernate's own sequence (after generation) by hand to 1 instead of 50? I
wouldn't need tausends of inserts per second...

Kind regards, Rawi

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